[philipkglass]

Solar PV performs better under imperfect illumination conditions. Concentrating solar thermal power can't make use of diffuse light on partly cloudy days, whereas solar PV can. Solar thermal also has to reach a minimum operating temperature before it starts generating steam/electricity. PV actually works better on bright, cold days and will generate full power the instant an array reaches full illumination. These factors, plus the greater mechanical complexity and maintenance requirements for thermal solar, make it very hard for new thermal solar plants to deliver a lower levelized cost of energy than new PV plants.